The invention relates to a method for measuring gas concentrations with a measuring probe which is supported with a global positioning system (GPS).
German patent publication 196 14 231 discloses a measuring device with a satellite-supported global positioning system in the form of an emergency calling device which is carried on the body of a patient and continuously measures certain vital parameters of the patient. When an emergency arises, the vital parameters and the current position data are transmitted to a central emergency call station. The known measuring device is intended to provide a fast and directed emergency response.
Devices for measuring gas concentrations at different locations are known. These devices are comprised of individual measuring heads which are arranged in a plurality of spaces. The measured values are transmitted to a central evaluation unit. Such a device is disclosed, for example, in German patent publication 26 55 271.
The disadvantage of this known measuring system is that the gas concentration measurements can be performed only at very precisely predetermined measuring locations.
It is an object of the invention to provide a method for measuring gas concentrations which permits gas concentrations to be detected at different locations in a simple manner.
A first embodiment of the method of the invention is for measuring gas concentrations with a measuring head having a data memory and communicating with a satellite-supported global positioning system. The method includes the steps of: determining position data of a position of the measuring head at preset time intervals and measuring gas concentration values at the position of the measuring head; comparing first position data of a previous first position of the measuring head with second position data corresponding to a current position of the measuring head and determining whether a predetermined limit value is exceeded; and, if the predetermined limit value is exceeded, storing the second position data together with a measured value of gas concentration corresponding to the current position in the data memory of the measuring head.
The advantage of the method of the invention is essentially that the measuring head, provided with a satellite-supported global positioning system, continuously determines the current position, compares this current position with a previously measured position, and stores the current position data together with a measured value of gas concentration in a memory of the measuring head when a significant positional change occurs. In this way, it is possible to establish a toxic substance register of the environment to be tested.
A second embodiment of the method of the invention includes the steps of: determining the position of the measuring head and measured values of gas concentration corresponding to the position at preset time intervals and storing the position and the measured values of gas concentration in the data memory of the measuring head; detecting current measured values of gas concentration within the time intervals; comparing the current measured value of gas concentration with a measured value of gas concentration last stored in the data memory to obtain a difference concentration measured value; and, if the difference concentration measured value exceeds a predetermined difference concentration threshold value, storing the current measured value of gas concentration in the data memory of the measuring head.
This advantageous second method of the invention is applicable in cases wherein a change of the gas concentration over time is to be measured.
For this purpose, the position of the measuring head and the measured value of gas concentration, which corresponds to that position, are determined at predetermined time intervals and the data are stored in the data memory of the measuring head. Further gas concentration values are detected within the time intervals and, in each case, compared to the gas concentration value stored last. A difference concentration measuring value is formed from the current measured gas concentration value and the measured gas concentration value stored last. The current measured gas concentration value is stored in the data memory only when the difference concentration measured value exceeds a predetermined threshold value. In this manner, significant gas concentration changes within the time intervals can be detected and documented.
Advantageously, the measured gas concentration values stored in the measuring head and the position data are transmitted to an evaluation unit in which the toxic substance register is generated. The transmission can take place, as is-known in the art, via a PC interface or via wireless transmission. When several measuring heads are provided, which transmit position data and measured gas concentration values to the evaluation unit, the position data can be used to determine the spacing of the measuring heads relative to one another or to calculate an average gas concentration along a measuring path between two measuring heads.
When several measuring heads are present, it is advantageous. to transmit to the evaluation unit the stored position data and the measured gas concentration values together with identifiers assigned to the measuring heads, respectively.